The present invention relates to a vehicle braking system, and more particularly to an emergency brake system suitable for a vehicle equipped with a pneumatically operated brake booster.
A conventional brake booster of this kind comprises a servo-chamber and a power piston operated by pneumatic pressure applied to the servo-chamber from a source of pneumatic pressure in response to operation of a brake pedal. It is, however, observed that if the pneumatic pressure decreases due to damage of the pneumatic pressure source, the brake booster may not be operated. This means that sufficient braking effect cannot be obtained only by depression of the brake pedal.